"Philadelphia got the green light Wednesday for a $2 billion storm-water plan that will transform the way the city deals with rain.

The 25-year plan, which has been hailed as a national model, envisions green roofs on office buildings, porous pavement on city streets and parking lots, and plants and trees with tubs of gravel below ground to hold water and stall runoff in a storm.

All would be designed to let rainwater seep back into the ground rather than gush into an aged sewer system where it mixes with raw sewage and overflows into streams and basements.

Officials of the city Water Department and the state Department of Environmental Protection on Wednesday signed a consent agreement - constituting official approval of the plan - in the atrium of the DEP regional headquarters in Norristown. In front of a 5,000-gallon cistern that collects rainwater for flushing the building's toilets, they clinked glasses of public water in a toast."